In situ XPS investigation of Pt(Sn)/Mg(Al)O catalysts during ethane dehydrogenation experiments

Calcined hydrotalcite with or without added metal (Mg(Al)O, Pt/Mg(Al)O and Pt,Sn/Mg(Al)O) have been investigated with in situ X-ray Photoelectron Spectroscopy (XPS) during ethane dehydrogenation experiments. The temperature in the analysis chamber was 450oC and the gas pressure was in the range 0.3 – 1 mbar. Depth profiling of calcined hydrotalcite and platinum catalysts under reaction, oxidation and in hydrogen-water mixture was performed by varying the photon energy, covering an analysis depth of 10-21 Å. It was observed that the Mg/Al ratio in the Mg(Al)O crystallites does not vary significantly in the analysis depth range studied. This result indicates that Mg and Al are homogeneously distributed in the Mg(Al)O crystallites. Catalytic tests have shown that the initial activity of a Pt,Sn/Mg(Al)O catalyst increases during an activation period consisting of several cycles of reduction - dehydrogenation - oxidation. The Sn/Mg ratio in a Pt,Sn/Mg(Al)O catalyst was followed during several such cycles, and was found to increase during the activation period, probably due to a process where tin spreads over the carrier material and covers an increasing fraction of the Mg(Al)O surface. The results further indicate that spreading of tin occurs under reduction conditions. A PtSn2 alloy was studied separately. The surface of the alloy was enriched in Sn during reduction and reaction conditions at 450°C. Binding energies were determined and indicated that Sn on the particle surface is predominantly in an oxidized state under reaction conditions, while Pt and a fraction of Sn is present as a reduced Pt-Sn alloy

Tetra­chlorido(2,3-di-2-pyridylpyrazine-κ2 N 1,N 2)platinum(IV)

In the title complex, [PtCl4(C14H10N4)], the PtIV atom is six-coordinated in an octa­hedral configuration by two N atoms from one 2,3-di-2-pyridylpyrazine ligand and four terminal Cl atoms. Inter­molecular C—H⋯Cl and C—H⋯N hydrogen bonds stabilize the crystal structure

Fabrication and Characterization of 3D Micro- and Nanoelectrodes for Neuron Recordings

In this paper we discuss the fabrication and characterization of three dimensional (3D) micro- and nanoelectrodes with the goal of using them for extra- and intracellular studies. Two different types of electrodes will be described: high aspect ratio microelectrodes for studying the communication between cells and ultimately for brain slice recordings and small nanoelectrodes for highly localized measurements and ultimately for intracellular studies. Electrical and electrochemical characterization of these electrodes as well as the results of PC12 cell differentiation on chip will be presented and discussed

Scalable continuous production of high quality HKUST-1 via conventional and microwave heating

Metal Organic Frameworks (MOFs) are materials with large surface areas and internal volumes, which result in a number of useful properties for applications such as catalysis, separations and gas storage. However, MOFs are challenging to produce at a large scale creating a barrier to becoming truly viable alternatives to current technologies. As a first step towards industrial scale manufacture, we demonstrate here the first scalable, continuous synthesis of high-quality HKUST-1 using ethanol as the solvent, resulting in a greener and potentially much more economical process (as solvent does not decompose and thus can be recycled). We also show that microwave heating can be used to produce HKUST-1 continuously, in timescales several orders of magnitude faster than by conventional heating. We demonstrate a novel approach to microwave assisted synthesis of HKUST-1, based on a recycle loop with microwave irradiation, which is scalable under both batch and continuous conditions and allows an independent control of microwave irradiation regime and the overall reaction time. The use of microwave heating for continuous production of HKUST-1 enabled STY of 400,000 kg m−3 d−1, which is higher than any production rates reported to date, even when using the preferred high yield solvent, DMF, and is 17 times more than the highest production rates reported to date for HKUST-1 in ‘ethanol-only’ systems

Controlling gold nanoparticle assembly on electron beam-reduced nitrophenyl self-assembled monolayers <i>via</i> electron dose

Electron beam lithography is a well-established tool suitable for the modification of substrate surface chemistry. It therefore follows that the deposition and self-assembly of nanoparticles on a surface can be directed using this method. This work explores the effect of electron dose on the electron beam lithographic patterning of self-assembled monolayers (SAMs) on gold surfaces. Electron beam irradiation of the sample induces conversion of the SAM terminal functional aromatic nitro (NO2) moieties to aromatic amino (NH2) moieties. The cationic NH2 functionalised regions direct the site-specific assembly of anionic citrate-passivated gold nanoparticles in aqueous solution at pH 4.5. Control of nanoparticle attachment to the SAM is demonstrated over the exposure range 5000–125,000 uC/cm2. Overexposure led to significant numbers of secondary electrons reaching the surface, causing conversion of functional aromatic moieties outside of the regions irradiated, which reduced feature quality and regional selectivity of adsorption

Scalable continuous solvothermal synthesis of metal organic framework (MOF-5) crystals

Metal–organic frameworks (MOFs) are well suited as nanoporous materials for applications such as gas storage, catalysis and in medical devices. Literature predominantly covers information on the batch synthesis of MOF-5, however, for an industrially viable product to be formed, bridging the gap to scalable continuous processing is essential. Here, we show that crystals of MOF-5 can be formed in a scalable solvothermal continuous process with a maximum space time yield of nearly 1000 kg m3 day1 . Analysis of the solid output as a function of time, in conjunction with variation of concentration of the feed supply, shows high purity MOF-5 is produced using a continuous system, with potentially high throughput on scale up. We also show that the output can be increased by increasing the concentration of reactants in the system, albeit resulting in a reduced surface area. The two most common solvents currently used for MOF-5 production are also compared to identify a more economically viable process

Chancen situierten Lernens in der Lehrerbildung - Theoretische Analyse und empirische Überprüfung -

Die vorliegende Arbeit beschäftigt sich mit der Frage, inwiefern Ansätze situierten Lernens in der Lehrerbildung dazu beitragen können, künftige Lehrer/innen besser für die komplexen Anforderungen an das Lehrerhandeln vorzubereiten. Auf der Grundlage einer theoretischen Analyse zum Lernpotenzial situierter Lernbedingungen in der Lehrerbildung unter Berücksichtigung der Persönlichkeitsvariable �Ambiguitätstoleranz� sind situierte Lernbedingungen für Erstsemesterstudierende des Lehramts an Grundschulen im Bereich Schriftspracherwerb und -didaktik konzipiert worden. Diese Lerneinheiten haben die Förderung diagnostischer und förderdidaktischer Kompetenzen zum Ziel. Die Effektivität der situierten Lerneinheiten ist in einem 2x2-faktoriellen Design mit den Faktoren �Ambiguitätstoleranz� (hoch vs. gering) und �Lernbedingung� (situiert vs. traditionell-textbasiert) überprüft worden (N=100). Dabei wurden lernbegleitende Prozesse (Motivation und Interesse, Gedanken zum Praxisbezug) und Lernergebnisse (Faktenwissen und anwendungsbezogenes Wissen) erfasst. Zudem ist die Akzeptanz der situierten Lerneinheiten mit Hilfe leitfadengestützter, fokussierter Interviews erhoben worden � von den vier befragten Probandinnen verfügten zwei über eine relativ hohe und zwei über eine relativ niedrige Ambiguitätstoleranz. Es hat sich gezeigt, dass eine domänenspezifische Umsetzung und Vernetzung sämtlicher Implementationsmerkmale situierter Lernbedingungen � das impliziert in der vorliegenden Studie auch einen strukturierten Theorie-Input � in hohem Maße geeignet sind, diagnostische und förderdidaktische Kompetenzen bei Lehrern zu fördern � unabhängig von der Ambiguitätstoleranz einer Person

Candidate - job recommendation system : Building a prototype of a machine learning – based recommendation system for an online recruitment company

Recommendation systems are gaining more popularity because of the complexity of problems that they provide a solution to. There are many applications of recommendation systems everywhere around us. Implementation of these systems differs and there are two approaches that are most distinguished. First approach is a system without Machine Learning, while the other one includes Machine Learning. The second approach, used in this project, is based on Machine Learning collaborative filtering techniques. These techniques include numerous algorithms and data processing methods. This document describes a process that focuses on building a job recommendation system for a recruitment industry, starting from data acquisition to the final result. Data used in the project is collected from the Pitchler AB company, which provides an online recruitment platform. Result of this project is a machine learning based recommendation system used as an engine for the Pitchler AB IT recruitment platform

Multilanguage is a source of knowledge in preschool. : A qualtitativ studie about preschool teacher's experiences in the use of strategies to support multilingual childrens language development in preschool.

Detta är en kvalitativ studie av fyra förskollärares arbete med att synliggöra strategier i förskolan i ett språkutvecklande arbete med flerspråkiga barn. Syftet med studien är att synliggöra hur förskollärare stöttar flerspråkiga barn i sin språkutveckling. Studien berör frågor som innebär att synliggöra kompetenser hos förskollärarna inom området flerspråkighet. Vidare kommer studien även beröra vilka strategier som tillämpas i förskollärarnas arbete med flerspråkiga barn. I denna studie har fyra förskollärare med liten till hög erfarenhet i mötet med flerspråkiga barn intervjuats. Vikten av att besitta erfarenhet spelade roll för resultatet, då erfarenheten skulle medföra hur arbetet ser ut för de olika förskollärarna. Studiens fokusområde har varit strategier och kompetenser samt hur arbetet utformas språkutvecklande i deras arbete med flerspråkighet. Studien vilar på semistrukturerade intervjuer som genomfördes via telefon.    Tidigare forskning där bland annat Fredriksson och Lindgren Eneflo (2019) lyfter vikten av att arbeta språkstimulerande med flerspråkiga barn i förskolan. Författarna benämner att barn med ett annat modersmål än svenska ska få rätt till likvärdig undervisning, genom att få möjlighet att utveckla sitt svenska språk och hemspråk. Likaså ges möjlighet till att utveckla sin kulturella identitet. Något som härstammar från skollagens bestämmelser samt läroplanen för förskolan. Resultatet för denna studie visar att förskollärarna tillämpar goda strategier och har ett synsätt som ställer sig i linje till det sociokulturella perspektivet som även tillämpas i denna studie. Resultatet lyfter även utmaningar i arbetet med flerspråkiga barn, samt vikten av att bemöta utmaningarna på ett rätt sätt.